I have an old-work 20 cu in junction box. It has two sets of 14-2 cables
spliced: two sets of travelers weren't long enough and had to be lengthened.
The box uses Ideal connectors which take very little space. All and all,
the wires already in there take about 1/4 of the available space.
I need to add an outlet to that box (same circuit) which I'm technically
not allowed to do. However, practically speaking, the box will hardly be
half full if I do this.
What would you do in this situation?
You didn't say why you're "technically not allowed to do this"?
I can only assume you said it because local code dont allow a
non-licensed electrician to do the work. (Which is rare if the
homeowner does his own work).
So, without knowing this reason, I can only say that if this was *MY
HOUSE*, I'd just add the outlet and shut up about doing it.Inspection
departments cant possibly keep a record of every outlet in every home.
If someone ever asks about it, just tell them it was there when you
bought the house. (Of course be sure to do it according to the code,
which mostly just means adding a bare or green grouns wire, and
splicing with the approved wirenuts, not tape). ANd use the same gauge
of wire too.
OK, some clarification.
I'm technically not allowed to do this because that would be too many
wires/devices. 20 cu in is the deepest single gang box available. And
with two sets of 14-2 wires spliced, I used up 17 cu in of nominal space
(2x4x2 + 1).
Yes, it's a 3-way/4-way switch circuit, but the neutral is delivered to
the electrical box with the switches by a different cable that does not
pass through this junction box.
So: by adding a 14-2 wire and an outlet to this box, I will technically
be going over the wire limit. But practically, the box will only be
about half full.
Ah, I got you. So you are going to have to pull another cable into the
box, that is what I was missing.
Do you have access to the backside of this wall? could you use a 1900
(4" square) box with a mud ring?
replace "roosters" with "cox" to reply.
As another poster said, given the description and particularly that it's
14-ga wire that is so flexible, I'd in all likelihood go ahead and
stretch the volume limit if it was truly near-impossible to retrofit the
larger box for some reason (other than just not wanting to do so).
While it might not be totally Code-compliant, if the conductors are not
kinked or rubbing on mount screws, etc., it is not going to be a safety
I've seen many, many boxes over the years that are absolutely crammed to
the limit of what could be gotten into them and none have ever been a
problem owing to that capacity limit.
So, it isn't quite kosher, but sometimes "ya' just gotta' do what ya'
gotta' do" when it isn't really going to be anything but a technical
violation, not a safety one.
$0.02, etc., etc., etc., ...
Where does that "+ 1" come from?
Here's what your calculation *should* look like:
4 14ga cables @ 2 conductors each = 8 conductors
add 1 for one or more equipment groundi ng conductors
add 1 for each cable clamp in use (presumably at least 2)
That's what you have *already*: the equivalent of 11 conductors, at 2 in^3
each, which means you're at 22 in^3 *now*. Not 17.
Then add 2 more for the device yoke you're planning to add. That brings the
total to 13 conductors x 2 in^3 each = 26 in^3 minimum.
That's his allowance for the EGCs, but it's not quite right. It
should be (2 * 4 + 1) * 2, or 18 in^3.
You only need to count clamps that extend into the box, so the
integral clamps on a plastic box do not need to be counted. Thus I
assume he's using a plastic box.
Plus, since we are talking about a one-gang box, for a plastic
one-gang and NM cable, you don't need to clamp the wire to the box, as
long as you secure the wire close enough to the box (I forget the
requirement). Single-gang plastic boxes typically don't have cable
clamps at all.
I, on the other hand, having observed that he didn't calculate the EGC
requirement correctly, just assumed he didn't know he was supposed to count
the clamps too.
Right, but I don't think he ever stated explicitly that it's a plastic box.
OTOH, he *did* state explicitly that it's an old work box -- which makes it
*very* unlikely that the cables are secured to the framing at all, let alone
within the required distance (which, BTW, is 8 inches).
While that is permitted with nonmetallic cable (Romex), it will cause
some EMI when the light on, since the neutral is not routed with the
hot conductors. It is generally a good practice to route your
cables together when the neutral and the hot/travelers are in
As to your OP, if I couldn't possibly fit a larger box there, I'd use
an additional box for the receptacle. And I'd feed it with a hot and
neutral together in the same cable.
I didn't entirely follow that from Sam, but all wires for a circuit need
to appear in the same cable; it seems to violate 310.3-B. I would
consider that more important than too many wires in the box. Sounded
like Sam was also considering adding a romex and an outlet in the box.
Another possible, but ugly, is a wiremold surface extension.
Anonymously ask the inspector his opinion about overfill in this box?
Box now has a blank cover?
I assume you mean 300.3(B). In which case see 300.3(B)(3), which
basically says the requirement doesn't apply to cables with a
non-metallic sheath, i.e. Romex. None the less, when circuit
conductors are split between multiple cables, it is a good idea to run
the cables together.
300.3 was rewritten a few codes ago and I had a distinct recollection
that California 3-ways that used 2 2-wire romexes were prohibited. Looks
like the weren't.
If the conductors are not together and with high current the magnetic
field from the loop can affect CRTs, as in old TVs. I guess CRTs are
You can definitely get them up to 24 in^3, although they will
obviously be bigger in some dimension and so might not fit in your
space. See, for example, www.aifittings.com. But you need 26 in^3
for what you want to do, and I don't know if those exist.
Why even bother thinking about this. No neutral means that you can
NOT put an outlet in there no matter how much box space is used. Put
the cover back on the box and put in a different box with a new run of
cable for your new outlet. You can put this new outlet near the old
box, or anywhere else you want it.
As a side note, the neutral most likely goes to the light fixture
directly and this box is used for the wires feeding a switch.
End of topic.
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